Field of the Invention
The present invention relates to a set of an ink and a print medium, an inkjet printing method, an inkjet printing apparatus, a printed matter, an ink, and an ink stored container.
Description of the Related Art
Hitherto, it has been common that inks used in inkjet printing methods contain colorants, organic solvents, and water. Dyes have been mainly used as the colorants because of an excellent chromogenic property and an excellent stability. However, images obtained with dye inks are insufficient durabilities such as light resistance and water resistance. The durabilities have improved to some degree along with improvement of dedicated inkjet printing paper having an ink absorbing layer. However, the durabilities on plain paper have not become satisfactory.
In recent years, pigment inks using pigments as colorants have come to be used. The pigment inks have been largely improved in image durabilities such as light resistance and water resistance, in which the dye inks lack. However, the pigment inks have a problem of imparting a poor glossiness because light interference occurs between different wavelengths or phases due to, for example, multiple reflection of light in the pigments.
Moreover, images obtained with the pigment inks may stain print media, because it is difficult for the pigments to fix on print media. This results in a poor scratch resistance of the images when the images are scratched with a finger or paper. Particularly, the pigments in the inks are more likely to remain on a surface of print media such as coated paper into which inks are not so easily absorbed as into plain paper. This results in a considerably poor scratch resistance.
In order to overcome the problems, there is proposed an ink intended for improving scratch resistance by containing, for example, polycarbonate polyurethane resin particles to form a hard ink coating film having a surface hardness of 100 N/mm2 or greater (see, e.g., Japanese Unexamined Patent Application Publication No. 2014-198824).
There is also a proposal for adding two kinds of resins having low and different glass transition temperatures (Tg) in an ink to improve a film forming property of an ink image and improve a film strength of a film formed (see, e.g., Japanese Unexamined Patent Application Publication No. 2007-76033).